Flexible doors



Aug. 28, 1956 o. c. ECKEL ETAL 2,760,567

FLEXIBLE DOORS Filed Jan. 5, 1953 2 Sheets-Sheet 1 FIG. 2

1 INVENTORS 1 OL/I/ERCECKEL u THEODORE c. BROWNE a Q HENR M. SPEL MA N, J N \l B V 6 Aug. 28, 1956 o. c. ECKEL ET AL 2,760,557

FLEXIBLE DOORS Filed Jan. 5, 1955 2 Sheefs-Sheet 2 INVENTORS OLIVER CEC/(EL THEODORE CBROWNE HENRY M. \SPELMAN, JR.

United States Patent FLEXIBLE DOORS Oliver C. Eckel, Boxhoro, Theodore C. Browne, Winchester, and Henry M. Spelman, Jr., Cambridge, Mass;

said Browne and said Spelrnan, Jr., assignors to said Eckel This invention relates to flexible doors.

The present invention has for its objects the elimination of door hinges, the reduction of the inertia of the door, the provision of a more expeditious and convenient method of door assembly, and the minimization of installation and maintenance expenses and labor.

We have discovered that a stile or a rigid support, even in an inflated door, can be dispensed with under some circumstances, neither is it necessary to make the door covering and door construction exceedingly strong and heavy to withstand the blows of a lift truck. If a door can be made to have relatively low inertia and can respond in a lively manner under a blow, an inflated door rolls with the punch and can absorb what otherwise would be a destructive impact without ripping or tearing. Additionally, we have found that the lighter door coverings make the use of hinges unnecessary, for a door with light, transversely flexible covering can bend about its support in the doorway and open in the manner of an ordinary hinged door. Also, if the door, as it opens, is forced against some fixed element of the doorway structure, the air pressure in the door casing reacts against that element to swing the door closed as soon as the door opening force is relaxed. Thus, the whole combination becomes a pneumatic door closing device.

Our preferred door construction is illustrated in the following figures of which Figure 1 is an elevation showing the door mounted in a door casing,

Figure 2 is a cross section through the door taken on the line 22 of Figure 1,

Figure 3 is an enlarged cross section of one face of the door,

Figure 4 is a horizontal cross section through a modified form of the door,

Figure 5 is a vertical cross section of the modified form of door shown in Figure 4, the cross section being taken at the top or the bottom margin of the door,

Figure 6 is a horizontal cross section of a further modification of the door, in which a separate interior bladder is used,

' Figure 7 is a horizontal cross section of a further modification of the door using a vertical marginal bladder, and Figure 8 is an elevation of a typical tapered spacing strip.

The door is wholly resilient and flexible, but is inelastic in the sense that the covering and the door is not stretchable as is, for example, gum rubber (details of its construction will be given later). It is supported in the door opening by a rigid clamp 11 formed from two right angle bars 12 and 13 placed back to back and engaging the entire support margin 14 of the door. Two guide nosings 15 and 16 are provided with slots 17 and 18 to permit lateral adjustment. These are placed against the outer face of the angle bars 12 and 13 and are held in position by the bolts 19 which hold the 2,760,567 Patented .Aug. 28, 1 956 assembly together. Clamp 11 is screwed or otherwise fastened to the door casing 20.

There are no hinges in the conventional sense, but instead, as Figure 2 shows (see the dotted outline of the door in open position), the door itself bends about the nosing, which presses into the inflated portion 21 of the door 10. The air pressure in the door reacting against the nosing 15 or 16 swings the opened door into the closed position as soon as the opening force ceases to act. In addition to acting as members which compress the inflated portion of the door body, guide nosings 15 and 16 serve three other important functions. First, they may be adjusted forward or back or further out at one end of the door than the other to hold the door accurately in its closed position. They thus may be considered as elements which define the closed position of the door. Second, the radius at the exposed end of the nosings limits and defines the bending radius of the door as it hinges or swings about the nosing, and this radius. 22 is chosen with regard to the flex life of the door material. Third, by adjusting thenosings to bear heavily or lightly on the inflated body, the speed at which the door closes may be adjusted; and conversely, the force required to open the door may be varied. This adjustment may be greatly widened by changing the air pressure in the door, which normally is between six and eight pounds.

Preferably, the door 10 is a unit with a large, uncompartmented inflatable portion 21, a surrounding noninflatable, flexible marginal portion 23, the margin on one side (support margin 14) having a suflicient lateral dimension to constitute a support for the door.

The door 10 is built up on a cross-tie fabric 24. This is a strong fabric woven on a plush or carpet loom, but instead of cutting the pile threads as is ordinarily done, the pile loops remain uncut so that the two continuous webs of fabric 25 and 26 are spaced apart but are joined together by the pile loops 27 which form stays holding the two webs 25 and 26 parallel to each other.

The strength of this fabric is obviously dictated by the conditions which the door is to undergo in service. For example, a top and bottom ply of approximately 36 by 40 construction with 20 pile loops providing 40 uniformly distributed tie threads to the square inch, consisting of No. 16 cotton yarn, is a satisfactory body for ordinary industrial service. Light pass doors permit much lighter constructions to be used, while doors which are to be subject to heavy abuse require far heavier cloth constructions. A large number of uniformly spaced tie threads are essential, if the faces of the door are not to assume a waffle pattern after the door is inflated.

When the door is inflated, the tie threads should-extend normal to both of the opposing Webs. They should not lie at acute or obtuse angles, for the diagonal pull of any substantial number of the tie threads will cause the inflated door to be distorted. To prevent distorted doors, we have found it highly desirable to introduce colored marker threads in the webs 25'and 26 at fixed intervals and then catch the fabric together by a stitch which passes through the intersection of the longitudinal and transverse marking threads of both plies. The threads which form this stitch should be strong enough to hold the two fabrics in register throughout any coating, cementing or combining operation which may be necessary in the manufacture of the door; and yet, relative to the strength of the tie threads, they should be weak enough so that they will break before the designed inflation pressure in the finished door is reached. After catching the dual fabric in this manner, it is heavily coated with a rubber cement, then cut to the size of the door desired. A strip of heavily rubberized fabric 28 is folded into a v. The margin of each open arm of the V strip is cemented, respectively, to the top and to the bottom web of the dual fabric 24 all around its margin. (See the cross section in Figure 2.) Were the dual fabric to be inflated at this stage, it would assume the shape of a shallow, straight sided, rectangular box, for, on inflation, the arms of the V unfold to make a vertical side wall.

As the next step in manufacture, a sheet of canvas 2% (for ordinary industrial service a sheet of 12-ounce duck) is heavily coated on its outer surface with an abrasion resistant rubber compound 31. The inner face of the canvas is covered with a layer of rubber 32 of sufiicient thickness and continuity as to be air impermeable. The air seal layer 32 together with its canvas support 29 is cemented to the face of one of the webs 25 and 26 and is brought into full contact with the cemented surface of the dual fabric by pressing or rolling. A duplicate of this outer covering 38 is laid on the opposite cemented dual fabric face and again brought into full contact with that face. The air seal layers 3232 are cemented and rolled or pressed together beyond the confines of the V strip at 33 so that a marginal outwardly extending flange 23 is formed on the median line of the door. Air valve patch 34 is applied to the casing. If desired, the margins 23 and 14 may be held in bar clamps, and the assembly is vulcanized. Open steam is satisfactory, but it is obvious that a wide variety of vulcanizing techniques can be used.

Besides permitting a simple and expeditious method of assembly, the median flange 23 makes a slight adjustment of the door to the size of the door opening possible. It has been so customary to plane the edges of a door to fit the door casing that, unless prefabricated steel door casings are used, door openings within a single warehouse or factory, although nominally of the same size, may vary as much as or /2 inch. The flange may be trimmed to overcome this variation, but there are instances where a flange is undesirable, and the modification which is shown in Figure 4 illustrates a method by which doors can be made which have no marginal outwardly extending flange except the supporting flange 14.

This may be accomplished by cementing a half round extruded section of rubber 35 to the face of a strip 36 of heavily rubberized fabric. The length of section 35 corresponds to the vertical dimension of the door, and its radius is half the door thickness less the thickness of the covering material. Where the strip extends across the top and bottom edges of the door, a square extruded section of rubber 37 is attached to the strip 36, the transverse dimension of which equals the thickness of the door less the thickness of the door coverings. Their rearward ends are tapered to correspond with the diminishing cross section of the door near its attachment portion 14. The edges of the fabric strip 36 are cemented to the upper and lower webs 2.5 and 26. No extruded rubber strip is used adjacent the supporting margin 14. Instead, the fabric strip 36 is folded into a V and cemented to the two webs in the manner which has been described.

The outer coverings 30 are cemented and butted together on the median line of the half round. They are also cemented against the exposed vertical faces of the square section of the rubber 37 as shown in Figure 5. This assembled door is vulcanized in open steam or in other appropriate manners.

As Figure 2 shows, the margin 14 in both forms of door is extended to a considerable width so that it may form the marginal attaching and supporting portion of the door element 10. It is punched at 3838 to match the bolt holes in the clamping bars 12 and 13. Then the clamp 11 and the guide nosings and 16 are assembled and bolted to the door completing the door assembly. The door 14? is then inflated to about 6 to 8 pounds pressure. Considerably before this pressure is reached, the catch threads break and the door thereafter is flat with plane, parallel faces.

This construction has numerous advantages. First, the

radius 22 is chosen with regard to the flex life of the flexible covering and prevents any sharp bend from occurring at the hinge point, no matter how violently the truck smashes into the door. Second, there is no open hinge space through which heat or cold may escape (an important consideration in cold storage food warehousing establishments). Third, since the door is supported along its whole margin and no concentrated bending stress can be built up because of the nosings, the door will Withstand the abuse of power fork trucks and their loads hitting it repeatedly. Yet the door closes dependably as soon as the truck drives through.

The modification shown in Figure 6 is a rugged structure which is particularly useful in doorways where the danger of the load or of the truck actually hitting the supporting structure of the door is high because of the small clearance. The door body may be the same as that which has been described, but since the heavy nosings are particularly useful in connection with heavy bladder type doors, such a door construction will be set forth as the preferred modification.

The nosings 3939 are preferably formed from heavy gauge metal and comprise an internal flange portion 41, a door clamping portion 42, a radius portion 43, and a deflecting return and mounting flange 44. The door body 45 comprises a casing 46 usually, but not necessarily, made of a multi-ply rubberized canvas. An abrasion resistant coating of a rubber compound covers the outer surface of the casing. The casing 46 is folded back on itself and at intervals the inner faces of the casing are cemented to a rubber I beam 4-7. Between the I beams the interior of the casing is filled with flexible, elastic air bladders 48. Then the inner margins of the casing are brought down against the spacer strip 49 and pinched together between the nosings 3939 by bolts 51. As the door swings about the nosings when it is pushed out, the inner marginal inflated area of the door is compressed, and the air pressure in the door then reacts against the nosings to close the door in the same manner as has been described above. Should such a door hang a bit out of its closed position, its hanging can be corrected by inserting a tapered spacer strip 52 between the nosing and the door casing on one side or the other. It is made thinner at the top or at the bottom as may be required to correct the hang of the door. Such a tapered spacer strip is shown in Figure 8.

The modification shown in Figure 7 is useful when it is necessary to have the opening and closing characteristics of the door different from that which would be permitted by the inflation pressure in the bladders of the door, as, for instance, when it is desired to have the door open easily, close slowly, yet be lively under and Withstand heavy traflic blows. It may be used in other door constructions such as that of Figure l but will be illustrated and described with a door of the separate bladder type (Figure 6).

At the end of bladder 48a a strip of rubber 53, usually of rectangular cross section is cemented to the two opposite inner faces of the casing 46; the strip 53 extends from the top to the bottom of the door. A flexible resilient tube 54 of rubber having closed ends and provided with an air valve 55 is placed between the open ends of the casing. The external diameter of the tube should equal or somewhat exceed the transverse interior dimensions of the door. The air valve is passed through a hole in the casing, and then the free ends of the casing are pushed against spacer strip 49a and held between the nosings 39-39 by the bolts 51. The rubber strip 53 or an equivalent pressure insulating means prevents tube 54 as it is compressed from merely pushing into'the bladders, and it makes it possible for the marginal area of the door to act in a relatively independent manner without regard to the pressure in the body of the casing. The examples have been given of doors which swing in both directions. It is obvious that, if the door is to open in one direction only, one of the nosings may be omitted.

Sponge rubber, particularly cellular sponge with discrete air cells, may be substituted for tube 54 with distinctly inferior results. Its compression and expansion to original dimensions will close the door, but it permits no adjustability either in opening pressure or in closing speed. Also with lapse of time, sponge rubber loses some of its resiliency, and the opening and closing characteristics of the door will progressively become more dead.

In the specification and claims, the word rubber has been used in its present day commercial sense to include not only natural rubber but also the various artificial polymeric substances which possess the resiliency, elasticity and other recognized rubberlike characteristics.

We claim:

1. A self-closing door comprising a door element having a body portion, a flexible casing on the outside of the body portion, a converging outward extension of the casing terminating in a marginal mounting flange coextensive with one edge of the door element, said flange having a thickness less than that of the body portion, the convergent area being flexible, and a rigid support element mountable on a door jamb and having clamping portions adapted to retain the marginal mounting flange at substantially a right angle to the door jamb, and a separate nosing portion adjacent the clamping portion on at least one side of the door, said nosing portion being laterally adjustable to contact the converging portion of the door element whenever the door element is swung against the nosing into its open position.

2. A self-closing door comprising a door element having a body portion, a flexible casing on the outside of the body portion, a converging outward extension of the casing terminating in a marginal mounting flange coextensive with one edge of the door element, said flange having a thickness less than that of the body portion, the convergent area being flexible, and a rigid support element mountable on a door jamb and having clamping portions adapted to retain the marginal mounting flange at substantially a right angle to the door jamb, and a separate nosing portion adjacent the clamping portion on at least one side of the door having its outer margin formed as an outwardly directed radius, said nosing portion having slots therein to facilitate adjustment thereof into position to contact that area of the door element which is in proximity to its supported margin whenever the door element is swung into its open position.

3. In a door element adapted when edge mounted in a doorway to form a self-closing door, an inflatable body portion and a surrounding non-inflatable, flexible marginal portion, the walls of said body portion being formed from a laminated sandwich consisting of two opposed fabric webs provided with a multiplicity of uniformly spaced textile strands extending transversely from web to web and an air seal layer of rubber material joined to the outer face of each of the webs throughout substantially its whole extent, said air seal layers extending beyond the confines of each of said webs and joined together beyond them to form an air tight hollow body, a flexible nonelastic fabric casing outside said body portion covering said body portion and joined to the air seal layer throughout the entire area of mutual contact, one of said marginal portions comprising a converging outward extension of said casing terminating in a marginal mounting flange coextensive with one edge of said door element, and having a lateral dimension suflicient to constitute a support for the element when the latter is rigidly connected to a door jamb and to project the inflated portion beyond the connection.

4. In a door element adapted when edge mounted in a doorway to form a self-closing door, a body portion with substantially parallel walls, a flexible casing on the outside of the body portion enclosing the body portion, a converging outward extension of said casing terminating in a marginal mounting flange coextensive with one edge of said door element, the flange having a thickness less than that of the body portion, said convergent area being compressible, resilient transversely flexible, and pneumatically inflated to permit the door to swing open and to close the door by reacting against a rigid element in the doorway structure, said mounting flange having a lateral dimension sufiicient to constitute a support for the element when the latter is rigidly connected to a door jamb and to project the inflated portion beyond the connection.

5. A mounting, support, and closing element for use in combination with a flexible door comprising two angle bars, means for fastening said bars back to back and to hold the entire support margin of a flexible door between them, at least one of said bars having a separate, laterally adjustable nosing having its outer edge terminating in a curve.

6. A mounting, support, and closing element for use in combination with a flexible door comprising a pair of bent members having door retaining portions adapted to extend perpendicularly from a door casing, means for fastening said members together and to hold the entire support margin of a flexible door between them, said retaining portions terminating in a curve directed outwardly away from said door retaining portions and merging into a blow-deflecting return portion extending rearwardly towards the base of said member.

References Cited in the file of this patent UNITED STATES PATENTS 

